Something is not right

The Goddamnitnotagain edition:

PA module with burned open output transformer

I went to do maintenance at one of our sites and noticed that a certain transmitter was running at half power. Followed the path of the fault log and found this. When I mentioned it to the station staff, they said, “Yeah, we noticed it sounded a little funny…”

This is the second time this has happened with this particular transmitter. In any case, this is what I get paid for, so I am certainly not complaining. If only every problem where this easy to find.

When I get back out there to replace this, I will bring out my network analyzer and sweep the antenna and transmission line to make sure there are not issues with that. In addition, I will double check all the grounding to make sure the copper thieves have not made off with any critical components like the ground buss bar or #2 solid down lead wires.

2 thoughts on “Something is not right”

My latest disaster was much harder to find. One of my clients had a lightning hit that took out a Harris HT-10. Once the step-start contactor with the open coil was replaced, there still were plate overloads. Went through everything in the HV and PA sections. Even had the line swept, which had never been done at that site before…all was well.

Stumbled across the cause by accident…on the back side of the plate transformer, the primary wires were dressed against the phase C secondary windings. The deterioration caused by the close contact finally resulted in a surge punching through the secondary winding into the primary. 7000+volts into a 240V circuit…glad nothing else blew up…the plate overload was tripping before the step-start had a chance to pull in.

Once the primary lines were dressed away, taped up with rubber and several layers of 33, the transmitter is back in business.

There’s a service bulletin for the BE FM20T and its cousins warning to check for this exact issue.